1. Field of the Invention
The present invention relates to power conversion and, more particularly, to a bi-directional direct current power converter for providing power to and obtaining power from electrical components.
2. Related Art
An electrical device may contain a variety of electrical components, each having different power requirements. Referring to FIG. 1, for example, consider an electrical device 100 powered by a DC power source 102. The device 100 contains a plurality of electrical components 106a-c coupled to and powered by a main DC power bus 104. Each of the components 106a-c may have different power requirements. The main power bus 104 has a higher voltage than that required to power any of the components 106a-c. 
Each of the components 106a-c typically draws DC power from the main power bus 104 using an internal step-down converter. For example, component 106a includes a step-down converter 108, which draws power from the main power bus 104 and converts it into DC power at a lower voltage suitable for an internal power bus 112 of the component 106a. The internal power bus 112 powers additional sub-components (not shown) within the component 106a. Although only the step-down converter 108 and internal power bus 112 of the component 106a are shown in FIG. 1 for ease of illustration, it should be appreciated that each of the other components 106b-c typically contains a similar step-down converter and internal power bus to draw appropriate amounts of power from the main power bus 104.
The main power bus 104 shown in FIG. 1 is a bi-directional power bus which not only provides power to the components 106a-c but which also allows the components 106a-c to provide power to the main power bus 104. In this way, power drawn from one of the components 106a-c may be distributed to one or more of the other components 106a-c over the main power bus 104. For example, as shown in FIG. 1, component 106a may include a step-up converter 110 to draw power from the internal power bus 112, convert it into the higher voltage power of the main power bus 104, and provide the converted power to the main power bus 104. Although only the step-up converter 110 of the component 106a is shown in FIG. 1 for ease of illustration, it should be appreciated that each of the other components 106b-c may contain a similar step-up converter to provide power to the main power bus 104.
The kind of design just described typically requires each of the components 106a-c to include both a step-down converter for drawing power from the main power bus 104 and a step-up converter for providing power to the main power bus 104. What is needed is a single bi-directional DC-to-DC power converter that can be used by components in an electrical device to efficiently draw DC power from the device""s main power bus and provide power to the device""s main power bus.
A bi-directional DC-to-DC power converter is provided. The power converter has three modes of operation: (1) a step-down mode, in which the power converter converts power in a first direction (such as from a high-voltage power bus to a low-voltage power bus), and (2) a step-up mode, in which the power converter converts power in the opposite direction (such as from the low-voltage power bus to the high-voltage power bus), and (3) an off mode, in which no power is transferred. A single power converter may therefore be used to replace both a conventional step-down converter and a conventional step-up converter. The power converter may provide a battery charge-control functionality, and may be used to charge a battery that may, for example, provide a source of power to a component of an electrical device.
Other features and advantages of various aspects and embodiments of the present invention will become apparent from the following description and from the claims.